| 摘要 |
PURPOSE:To execute microinstruction again while obtaining microsubroutine constitution only by adding plural registers and a small-scale control circuit without increasing the number of instruction decoders. CONSTITUTION:One machine cycle of a microprocessor is controlled by a four- phase clock in periods T1-T4. Each microinstruction 2 is executed in pipeline mode in two machine cycles and a control storage device (CS)26 is accessed on the basis of an address from an address selecting circuit 37 in the periods T1- T3 of the 1st machine cycle and a read microinstruction is read to a control register 40 by the clock; and the read microinstruction is converted in the period T4 into a control signal for controlling a computing element, etc., by a control part 27. Then, arithmetic operations are carried out in the periods T1-T3 of the next machine cycle according to the control signal. |
